1. Field of the Invention
The invention relates to a device for discharge limitation and simultaneous temporary storage of waste water and also to the separation of settleable and floating matter from foul water.
The invention also relates to such a method.
2. Description of the Prior Art
Discharge limiters in which the constrictive action is produced by the spin effect of a vortex flow are disclosed, for example, in German Patent Specification 507 713 and German Patent Specification 26 43 029.5. It is also known that there are cyclone separators which temporarily store the foul water and that a foul-water treatment takes place, as, for example, in German Patent Specification 36 34 122. However, these devices offer at best two or three possible combinations of discharge limitations, storage and separation of settleable and floating matter from foul water.
For environmental protection reasons, untreated foul water should not be fed into the water recirculation system. In the case of heavy rainfalls, however, the sewage treatment plants are incapable of further treating the foul water arriving from the catchment areas, with the result that some of the foul water is temporarily stored in storm-water retention tanks. In this case, it has to be ensured that, during the rainfall and thereafter, only a certain acceptable quantity of water is supplied to the sewage treatment plant from the storm-water retention tank. As a rule, this is achieved by constricting the flow cross section, by diaphragm-like or nozzle-like devices, by the generation of frictional losses in long constricting sections or by the spin effect of a vortex flow (so-called vortex constriction).
In the case of fairly heavy rain persisting for a prolonged period, it may happen that the storage volume of the storm-water retention tank is no longer adequate. The storm-water retention tanks then allow the untreated excess foul water to run into the receiving water course virtually without any treatment. In addition to the discharge limitation, there are consequently efforts to carry out also a more extensive storm-water treatment in future in the form of a pollutant separation in order to protect the receiving water course against anthropogenic contamination.
Hitherto, however, only the requirement of discharge limitation has generally been fulfilled by the devices described above. On the other hand, no methods are known in practice which achieve a discharge limitation and simultaneous temporary storage of waste water and also separation of settleable and floating matter from waste water with one device.